Valve for wireless telegraphy or telephony



July'l7il934. J. A'. M. HAWADIER 1 1,967,207

VALVE FOR WIRELESS TELEGRAPHY OR TELEPHONY FiledJfiiy-l; 1926 4-J d7 111:1;1- I} 311:1: T I

Patented July 17, 1934 ,VALVE FOR WIRELESS TELEGRAPHY OR TELEPHONY Jacques Antoine Marie Hawadier, Paris, France, assignor, by mesne assignments, to Old Colony Trust Company, a corporation of Massachusetts Application July 1, 1926, Serial No. 119,912

r In France July 10, 1925 A 3 Claims.

This invention relates to a valve for wireless telegraphy and telephony particularly constructed with the object of allowing the use of alternating current or more generally of current from the town supply for heating the filament thereby doing away with the use of a storage battery or the like as generally employed.

It is well known that the inconvenience which has prevented to this day the use of alternating current resides in the continuous variation of the polarity of the heating filament and consequently the permanent inversion of its action upon the plate.

With the object of doing away with this inconvenience the device constructed according to my invention contemplates the use in wireless valves of a double compensated filament in place of the single heating filament generally in use. To this end the valve then comprises two heating filaments or two filament parts or elements through both of which an inverse current flows simultaneously in such a manner that their action is reciprocally compensated and that the resulting effect upon the plate does not produce any modification in the polarity. The two filaments or filament-parts are themselves specially constructed in order to allow them to be emitting at low temperatures and on the other hand to cause only a slight cooling during the intervals between the alternations of current in such a manner as to do away with the dangerous efiects of alternating current.

To this end each filament or filament part comprises a thick metal core that emits electrons at relatively high temperatures only, such as tungsten or molybdenum and a covering constituted by an outer winding of a long fine wire of thorium or containing thorium, that emits at much lower temperatures. As the outer transmitting wire has a high resistance in fact much higher than that of the core, the result is that the alternating heating current does not fiow in said winding but 'is shunted through the core. This mode of construction results in the elimination of the-two dangerous effects of the alternating current, that is: alternation of'its action in the transmitting device (prevented because the current does not flow through same); and changes of temperature (brought down to the lowest possible. degree through the increase of the metal body of the whole filament).

Finally my invention has for its object the arrangement and the balancing between compensated filaments of a Wheatstone bridge the apex 'of which will thus constitute the'neutral point to be connected to the negative pole of the plate tension source.

The foregoing and other objects of my invention will be best understood from the following description of exemplifications thereof, reference being had to the accompanying drawing,

wherein: 1

Fig. 1 shows a Wheatstone bridge arrangement of the double compensated filament;

Fig. 2 illustrates a different arrangement of the general system shown in Fig. 1;

Fig. 3 illustrates a special mode of mounting of the compensated filaments; and

Fig. 4 shows a modified form of construction of my cathode.

Referring more particularly to Fig. 1, the valve consists of two similar filaments a, b, the filament being connected at c and d to conductors e and 1, respectively, coming from the stem g of the valve, while the second filament b is connected atj and k to the conductors e and 1, respectively by means of wires 71. and 2'. These wires h. and i are of some suitable material, such as, for example, copper, which does not become red hot and consequently is non-emitting.

As will be seen, the current divides at 7' into two parts: one part flowing in the filament a, as indicated by the arrow Z, and the other part flowing in the filament b in the opposite direction, as indicated by the arrow m. When the direction of the current is reversed at the next alternation, the direction of the current in both filaments will be reversed. Thus the currents flowing in the two filaments will always flow in opposite directions to each other. Since both emitting filaments a and b are exactly similar in their construction, their action will compensate each other in each direction of current fiow. This compensating action will be independent of the direction of current fiow.

Moreover, owing to the relatively large volume and mass associated with the emitting filament, the filament will not cool oii between the alternations of current so that the change in temperature of the emitting filament will be minimized and the undesirable action due tothe alternating current will consequently be greatly decreased.

The cathode described above can obviously be used in any space discharge tubes, such as a valve having the usual plate and grid.

The heating filaments are both constituted preferably by a thick wire s of tungsten, molybdenum, or any other material having similar properties. Around this wire is wound a much finer and longer wire 15' containing thorium and Ill) j quantity of emitting oxides.

having consequently a greater resistance. This fine wire, due to its material, its transverse section, and its length will emit electrons at much lower temperatures. Owing to its resistance it will be shunted around the core s and the alternating heating current will not fiow through it.

The Wires 5 of the filaments a, b are connected at suitable points A, B by wires of tungsten or other similar material forming the arms 11, n of a Wheatstone bridge, the apex of which constitutes a neutral point to be connected to the plate circuit in such a manner that there is no difference of potential between the points A and B whenever current flows throughthe fila ments. Said point is then connected with the negative terminal of the plate voltage source through wire 0.

The arrangement may be that shown in Fig. 2 in which a wire it helically wound and having no other contact with a, b is connected to point A, and the wire n similarly wound but in the reverse direction and of equal resistance is connected to point B. These wires 11', n reach points N, N between which the potential is the same. Said points N, N are then connected together to form a neutral point N. From this neutral point a wire 0 is connected to the negative terminal of the platevoltage circuit as described above. In each of the arrangements shown in Figs. 1 and 2, the points A, B are not taken from the core of the filaments, constituted as above described by a thick tungsten wire, but from the emitting covering formed, for example, of a fine wire containing thorium and having a higher resistance, so that the core may shunt its covering and so that only very little current flows through said covering.

The emitting member may also be constituted by incorporating in a soft conducting body a large This may consist, for example, of an asbestos string in which the emitting oxides and powdered tungsten are incorporated simultaneously by means of a strong compression. These oxides may then be reduced by heating at a temperature of about 1890" C. In order to insure a good connection from one end of the string to the other, a conducting core of some suitable metal, such as molybdenum having a large cross-section, may be used.

The double compensated filament may be mounted, as shown in Fig. 3, by means of an insulating supporting rod P of glass, quartz, or other suitable material, provided at both ends with a ball p of the same material, in which metal hooks having a double groove q are fixed. Each upper hook is placed above the middle of the space between two lower hooks. Two wires a, b constituted according to the present invention are wound alternately up and down in the grooves of all of the hooks. These hooks are preferably coated with an insulating varnish or enamel layer. The wires so wound are disposed so as to constitute conductors similar and parallel to each other. The end connections are made on the terminal conductors e, f in such a manner that at each alternation of the voltage applied to the terminals e and 1, current flows in opposite directions through both filaments. Any r sultant fields set up around the filaments by the heating current will consequently be eliminated.

Wires a, 11 preferably of molybdenum, are

connected to the midpoints (from standpoint oi resistance of the two filaments. These wires n and n are connected to the neutral point N, which in turn is connected as explained above.

In a valve utilizing the filaments as described above, the grid may be constituted by a fine wire placed opposite the emitting filaments and engaging separate long hooks.

In the modification shown m Fig. 4, the filament is constituted by a thick tungsten Wire 7" containing thorium. In this way two additional wires a, b are inserted. The latter have a low resistance and may be made of some suitable material, such as nickel. These wires receive alternating current through the conductors e and f, respectively, as indicated in Fig. 4. The thick wire 1 has a metal coating of higher resistance than the core, and is coated with emitting oxides. Two conducting wires n, n ending at the point N are connected to said coating. As will be seen in the drawings, the arrows in full lines and in dotted lines show the direction in which the current flows between the two nickel wires in both alternations. A second filament is connected in the manner shown in Fig. l. The neutral point is obtained by connecting the two points N of both filaments.

What I claim and desire to secure by Letters Patent of the United States is:-

1. A cathode for an electron discharge tu e comprising a plurality of filaments substantially parallel to each other, all of said filaments being connected to a common source of potential, said filaments being supplied with currents flowing through adjacent filaments in opposite directions, means for electrically connecting the centers of the electrical resistances of each of said filaments, and a conductor leading from said common connection to the outside of the tube.

2. A cathode for an electron discharge tube comprising a plurality of elements substantially parallel to each other, each of said elements comprising a conducting, non-emitting body portion, and a coil of electron-emitting wire surrounding said body portion, said coil of wire being of higher electrical resistance than said body portion, means for supplying said elements with currents flowing through adjacent elements in opposite directions, a conductor leading to the outside of said tube, and means for electrically connecting said conductor to the center of the electrical resistance of each of said coils of wire.

3. A cathode structure for an electron di charge tube comprising a filament forming a substantially closed loop enclosing an appreciable area, lead-in terminals connected to the ends of and closely adjacent said filament, a second filament parallel to said first-named filament throughout its length, forming a similar loop and electrically connected to said first-named file" ment at the points where said first-named filament is connected to said lead-in terminals, the current supplied from said terminals flowing through adjacent parallel filament sections in opposite directions, means for electrically interconnecting said filaments at the center of the electrical resistance thereof, and means for electrically connecting said last-named interconnected points to a third lead-in terminal.

JACQUES ANTOINE MARIE HAWADIER.

CERTiFlCAIE CORRECTION.

Patent No. 1,967,207. July 17, 1934.

JACQUES ANTOINE MARIE HAWADIER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 52, for the letter "F" read p; and line 132, claim 3, strike out the words "and closely adjacent" insert the same before "said" in line 133, of said claim; and that the said Letters Patent should he read with these corrections therein that the same may conterm to the record of the case in the Patent ()ifice.

Signed and sealed this 11th day of September, A. D. 1934.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

